Heretofore, in the usual steam sterilization process for a liquid filler system, it has been customary to apply a suitable adapter at the discharge end of the valve unit in order to maintain sufficient back pressure of steam in the system to effectuate the proper sterilization temperature. Once such a sterilization process is completed, there is not only some difficulty in removing the heated adapter, but also in maintaining sterility on and around the valve and discharge surfaces and on any internal surfaces exposed to the atmosphere.